To fail to meet someone's expectations or hopes; to let someone down.
From Old French 'desappointer,' combining 'des-' (away from) and 'apointer' (to appoint). It originally meant 'to remove from office' before evolving to mean 'to fail to satisfy expectations.'
The word 'disappoint' used to literally mean 'to fire from a job'—now it means to let someone down emotionally! This shows how words evolve from concrete actions to abstract feelings.
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